Optical Sensor Module Miniaturization via Wirebonded Ball Stacks
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Solution Overview
Problem
Traditional optical sensor modules for proximity sensors are susceptible to mechanical shock and occupy significant space due to their configuration, which uses a flex circuit to mount photodetectors and light sources separately, making them less suitable for miniaturization and integration in portable devices.
Innovation Solution
The use of pillars of stacked wireballs for vertical connections between a module substrate and optical components, along with a molding compound layer and a wiring layer, reduces the volume and height of the sensor modules, allowing for a more compact and robust design that embeds multiple components into a single module, thereby mitigating mechanical shock and optimizing space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional flex circuit configuration is used to mount photodetectors and light sources separately, then the optical sensor module can be assembled with conventional components, but the module occupies significant space and is susceptible to mechanical shock
Solution Approach 1:
The patent merges the photodetector and light source mounting structures into a single integrated module substrate, eliminating the need for separate flex circuit assemblies. This consolidation reduces the overall module volume and improves mechanical shock resistance by creating a unified structure with fewer separate components that could be damaged during impact events.
Solution Approach 2:
The patent transitions from a planar flex circuit layout to a three-dimensional stacked architecture using wirebonded ball stacks that extend vertically from the module substrate. This dimensional change allows components to be arranged in multiple layers, significantly reducing the horizontal footprint and overall module volume while maintaining electrical connectivity.
2Ease of manufacture
If separate mounting of photodetectors and light sources on flex circuit is used, then component assembly is straightforward, but the module height and footprint are increased
Solution Approach 1:
The patent employs wirebonded ball stacks that create vertical electrical connections between the module substrate and optical components, transitioning from a two-dimensional planar layout to a three-dimensional stacked configuration. This approach maintains manufacturing simplicity through standardized wirebonding processes while dramatically reducing the module footprint by utilizing the vertical dimension for component placement and interconnection.
3Productivity
If conventional optical sensor module configuration is used, then standard assembly processes can be applied, but the module is not suitable for miniaturization in portable devices
Solution Approach 1:
The patent combines multiple optical components (photodetector, light source) and their mounting structures into a single integrated module substrate with unified electrical interconnections. This merging enables more efficient integration into portable devices by reducing the total component count and assembly steps, thereby improving productivity while simultaneously reducing module volume for miniaturization applications.
Solution Approach 2:
By implementing vertical wirebonded ball stack connections and stacked component arrangement, the patent enables high-density integration in the vertical dimension. This three-dimensional configuration allows multiple components to occupy a smaller horizontal footprint, achieving miniaturization suitable for portable devices while maintaining efficient integration processes through standardized vertical interconnection methods.
Data Source
AI summary
Optical sensor modules and methods of fabrication are described. In an embodiment, an optical component is mounted on a module substrate. In an embodiment, a pillar of stacked wireballs adjacent the optical component is used for vertical connection between the module substrate and a top electrode pad of the optical component.